Question

I can draw a basic free body diagram, but I can never do the complicated ones. ..
Can anyone throw me a complicated FBD and explain it along the way while I ask questions please..?

Answer 1

They aren't really that complicated. All you have to do is try to work out what direction each force must act. It doesn't matter how many forces there are. It'd be easier if you gave us a question from your class.

Answer 2

I have an example.
I was also wondering when to make the lines symmetric.

Answer 3

I'm not sure what you mean by symmetric.

The question isn't very clear in the first place, which makes drawing the FBD more difficult. Are they supposed to be jumping straight up, or forward?

If forward, you'd have the vertical normal force (which must be larger than their weight mg, for them to jump up), and the horizontal friction force pushing them forward.

When they land, mg will be greater than the normal force initially when the foot hits the ground, and then increase to be larger than mg (in order for them to come to a stop vertically).